1. FIELD OF THE INVENTION
The present invention relates to material which may be used to wrap rolls or sheets of metal that is both tear and puncture resistant, and particularly to laminated thermoplastic materials.
2. DESCRIPTION OF THE RELATED ART
Various materials have been made with combined layers of material so that the final product exhibits the properties of both layers. No materials exist, however, possessing the unique properties of the present invention, including tear resistance, puncture resistance and corrosion inhibitors.
U.S. Pat. No. 2,742,388 issued Apr. 17, 1956 to A. W. Russell discloses a method of bonding and curing two or more plastic sheets to provide enough rigidity for use as structural members. The cellophane strip longitudinally between the edges to form a pocket in which a shaping tool may be inserted with the application of heat to soften and shape the fibers.
U.S. Pat. No. 3,130,647 issued Apr. 28, 1964 to W. E. Anderson, et al. describes a method of bonding a resilient or fragile layer to a relatively nonresilient layer, such as paper, by heat bonding with the application of pressure. U.S. Pat. No. 3,715,251 issued Feb. 6, 1973 to J. S. Prentice teaches lamination of nonwoven mats of thermoplastic fibers by adhesives or point welding to produce a laminated non-woven sheet of material.
U.S. Pat. No. 4,668,566 issued May 26, 1987 to Ralph V. Braun discloses a multilayer material comprising a layer of polyethylene bonded to a layer of polypropylene to form a nonwoven fabric. U.S. Pat. No. 4,748,070 issued May 31, 1988 to David C. Beehler teaches a polypropylene web bonded to a polypropylene film to increase the tear strength of the film. U.S. Pat. No. 4,749,423 issued Jun. 7, 1988 to Vaalburg, et al. describes a method of bonding a nonwoven web of thermoplastic fibers.
U.S. Pat. No. 5,272,023 issued Dec. 21, 1993 to Yamamoto, et al. describes a method of making a hot melt adhesive fiber sheet. U.S. Pat. No. 5,342,469 issued Aug. 30, 1994 to Bodford, et al. discloses a method of laminating a spunbond web of polyethylene fiber to a film using adhesive in which the adhesive layer is discontinuous. U.S. Pat. No. 5,424,115 issued Jun. 13, 1995 to Ty J. Stokes teaches a method of point bonding sheets of conjugate fibers such as polyolefin and polyamide fibers.
Canadian Patent No. 639,751 published Apr. 10, 1962 teaches a method of spot welding polyethylene film sheets. French Patent 1,307,386 published Sep. 17, 1962 describes methods of bonding sheets of plastic materials. German Patent 1,490,626 issued Aug. 13, 1963 describes an insulating paper for high tension wires bonded by spot adhesives. Japanese Patent 52-43594 describes bonding paper or cloth to a polypropylene base by adhesives. Japanese Patent 60-68934 describes a waterproof laminate composed of three layers, the second being polyurethane.
U.S. Pat. No. 4,290,912, issued Sep. 22, 1981 to Boerwinkle, et al., describes an article having volatile corrosion inhibiting properties, the article being a polyolefin polymer to which a mixture of an inorganic nitrite salt, a 2,4,6-trisubstituted phenol containing 9 to 24 carbon atoms, and fumed silica is added. The use of volatile corrosion inhibitors in packaging materials and to protect steel from corrosion is discussed in Corrosion, Vol. 2 (Sheir, L. L. and Jarman, R. A., eds.), published by Butterworth Heinemann in 1994, pp. 17:6 to 17:9, and in Steelwork Corrosion Control, D. A. Bayliss and K. A. Chandler, published by Elsevier in 1991, pp. 318-320.
Various methods of forming nonwoven fabrics generally, are discussed in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 10, pp. 546-47. A further description of forming nonwoven, spunbonded plastic fabrics is disclosed in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 17, pp. 303-309 and 336-338, and their use as packaging for steel and aluminum coils is particularly disclosed at p. 366.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. None of the above inventions and patents describe a material combining tear and puncture resistance with corrosion inhibition suitable for wrapping rolls or sheets of metals such as steel and aluminum. Thus a tear/puncture resistant semi-laminate material solving the aforementioned problems is desired.